<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        *{
            margin:0px;/*去掉自带外边距*/
        }
        #d1{
            width: 100px;
            height: 100px;
            border: 1px solid red;
           /* margin-left: 50px;
            margin-top: 50px;
            margin-bottom: 50px;*//*单独某一个方向赋值*/
            /*margin: 50px;!*四个方向符*!*/
            /*margin: 10px 100px;!*上下和左右赋值*!*/
            margin: 10px 20px 30px 40px;/*上右下左*/
        }
        #d2{
            width: 100px;
            height: 100px;
            border: 1px solid blue;
            /*上下相邻彼此添加外边距取最大值*/
            margin-top: 20px;
        }
        #s1{
            border: 1px solid blue;
            margin-right: 50px;
            /*margin-top: 50px;*/ /*行内元素上下外边距无效*/
        }
        #s2{
            /*左右相邻彼此添加外边距相加*/
            margin-left: 30px;
        }
        #big{
            width: 200px;
            height: 200px;
            background-color: red;
            overflow: hidden;
        }
        #big>div{
            width: 50px;
            height: 50px;
            background-color: green;
            margin-left: 50px;
            /*当元素的上边缘和上级边缘重叠时
            给元素添加上外边距会出现粘连问题*/
            margin-top: 50px;
        }
    </style>
</head>
<body>
<h1>这是h1</h1>
<p>这是p标签</p>
<ul>
    <li>是对的</li>
    <li>是大V</li>
</ul>
<div id="big">
    <div></div>
</div>
<span id="s1">span1</span>
<span id="s2">span2</span>
<div id="d1"></div>
<div id="d2"></div>
</body>
</html>